Description

We hit the tool_use/tool_result mismatch bug (#1685) through a compaction-specific path that isn't fully covered by the existing reports.

Our Reproduction

1. Agent (Elliot/forge) ran a heavy session: 855 messages, 218K tokens — lots of image analysis, screenshots, file writes
2. Safeguard compaction fired at the token limit (218,109 tokens)
3. Compaction pruned older messages including some tool_use blocks
4. Agent continued working after compaction — more tool calls from 15:20-15:26
5. At 15:26:30, agent called write tool → result was a synthetic error: [clawdbot] missing tool result in session history; inserted synthetic error result for transcript repair.
6. The synthetic result's tool_use_id (toolu_01ApYXdC1pESwmh5Tek2bMTq) referenced a tool_use block that had been pruned during compaction
7. Every subsequent API call failed permanently

Key Difference from #1826/#2087

Those issues focus on interrupted/terminated tool calls (stopReason: "error"). Our case is different:

• The tool call was not interrupted — the agent was actively working
• The corruption came from compaction separating paired messages — the tool_use was in older history that got summarized away, but the tool_result survived in recent messages
• The compaction summary itself already noted a prior repair: "Tool Failures: image: [clawdbot] missing tool result in session history"

Suggested Fix (extends #1826's proposal)

In addition to skipping errored assistant messages, repairToolUseResultPairing() should also:

1. Validate that referenced tool_use blocks exist in the active context before inserting synthetic results
2. Drop orphaned tool_results whose tool_use was compacted away (rather than keeping them)
3. Post-compaction: re-validate tool_use/tool_result pairing integrity

Environment

• Clawdbot version: 2026.1.24-3
• Provider: Anthropic (Claude Opus 4.5)
• Channel: Discord (multi-agent setup, forge agent)
• Compaction mode: safeguard
• Context pruning: cache-ttl, 1h TTL

Workaround

Deleted the corrupted session JSONL + cleared sessions.json, restarted gateway.